The present invention relates to the surface treatment with functional derivatives of perfluoropolyethers, particularly in order to provide oil- and/or water-repellency.
It is known in the art to use, for the surface treatment, fluorinated acrylic compounds and polymers containing perfluoroalkanes or perfluoropolyethers in graft position (U.S. Pat. Nos.2,803,615; 2,839,513; 2,995,542; 3,356,628 in the name of 3M; U.S. Pat. No.3,814,741 in the name of this same Applicant), surfactants and monofunctional derivatives with a perfluoroalkyl chain, for example perfluoroalkylphosphates for the oil-repellency treatment of paper (U.S. Pat. No.5,271,806), silicones and fluorosilicones, and polyurethanes fluorinated by bifunctional perfluoropolyethers (U.S. Pat. Nos. 4,983,666; 5,068,135 in the name of this same Applicant).
In particular, U.S. Pat. No.4,499,146 discloses the use of perfluoropolyethers with perfluoroalkyl endgroups to protect building materials such as marble, stone, bricks, cement and the like against the action of atmospheric agents and pollutants. These products provide oil- and/or water-repellency, are characterized by high permeability to gases and vapors and do not alter the appearance and color of the materials to which they are applied. However, on porous materials the protective action of these compounds decreases over time as a consequence of the migration of the perfluoropolyethers from the surface toward the inside of the material.
Better results have been reported for the use of perfluoropolyethers functionalized with groups capable of anchoring the product to the substrate to be protected. The use of said derivatives, functionalized with carboxyl, ester, amide, hydroxyl, diisocyanate, epoxy, silane groups etcetera to protect building materials against the action of atmospheric agents and pollutants is disclosed in U.S. Pat. No.4,745,009. Various other functional derivatives of perfluoropolyethers are disclosed in U.S. Pat. No.4,085,137.
Moreover, U.S. Pat. No.3,492,374 discloses the use of phosphoric esters with a perfluoropolyether chain having the formula I EQU [XCF.sub.2 CF.sub.2 O(CFXCF.sub.2 O).sub.x CFXCH.sub.2 O].sub.2 PO(OM) I
where X is --F or --CF.sub.3 ; x is an integer from 1 to 8; M is a cation, such as H.sup.+, an alkaline metal ion, or an ammonium ion, optionally alkyl-substituted; PA1 in order to impart oil-repellency to materials such as fabrics, fibers, hide, paper, plastic claddings, wood, ceramics. PA1 where L is a divalent organic group; m=1; Y is --F or --CF.sub.3 ; Z.sup.+ is chosen among H.sup.+, M.sup.+ where M is an alkaline metal, N(R).sub.4.sup.+ where the R groups are mutually identical or different and are H or C.sub.1 -C.sub.6 alkyls; R.sub.f is a chain of polyperfluoroalkylene oxide, PA1 for imparting oil- and water-repellency to surfaces made of ceramics, particularly Tuscany terracotta tiles, so-called "cotto toscano".
Besides, EP-A-603697 discloses the use of a compound having the formula II ##STR1##
The use of the same compounds to impart oil- and water-repellency to cellulose materials, metallic materials, glass-like materials, cement, marble and the like is disclosed in EP-A-687533.